Disclosed is an apparatus for use in the retrieval of an intravascular filter which has previously been emplaced in a blood vessel. Also disclosed is a method for using the disclosed apparatus in the retrieval of an intravascular filter.
A need for an intravascular filtering device can arise, for example, in trauma patients, orthopedic surgery patients, neurosurgery patients, or in patients having medical conditions requiring bed rest or non-movement. During such medical conditions, the need for filtering devices arises when there is a likelihood of thrombosis in the peripheral vasculature of patients wherein clot material, stenosis material or other particles break away from the vessel wall, risking downstream blockage of the vessel or other damage. For example, depending on the size, such break-away material could post a serious risk of pulmonary embolism, i.e. wherein blood clots migrate from the peripheral vasculature through the heart and into the lungs. A filtering device can be deployed in a vasculature of a patient when, for example, anticoagulant therapy is contraindicated or has failed. In more recent years, filters have been used or considered in preoperative patients and in patients predisposed to thrombosis which places the patient at risk for embolism.
The design focus of an intravascular filter of the type described, such as an IVC filter, is on providing a structure which is capable of trapping these emboli so as to prevent them from reaching the heart and lungs. The specific focus of the disclosed apparatus and method, as exemplified by the illustrated and described embodiments, is directed to retrieval of an intravascular filter which has been emplaced in the inferior vena cava (IVC) and then removal of that intravascular filter from the patient. The IVC represents a preferred placement location in the patient in order to address concerns over emboli which may originate in the veins of the leg or pelvis, i.e. deep vein thrombosis (DVT). For such emboli the flow path to the heart and lungs includes passage through the IVC. As used herein, the term “emboli” refers to something which travels through the bloodstream and which has a structural configuration such that it could become lodged in a blood vessel and create some degree of blockage to flow through the blood vessel.
The benefits of an intravascular filter have been well established. However, in many cases such filters have not been considered removable from a patient due to the likelihood of endotheliosis of the filter or fibrous reaction matter adherent to the endothelium during treatment. Following deployment of an intravascular filter in a patient, proliferating intimal cells can begin to accumulate around the filter struts which contact the wall of the vessel. After a length of time, such ingrowth may prevent removal of the filter, or may risk significant trauma during removal through a layer of endothelium, requiring the filter to remain in the patient.
The focus of this disclosure is on the method of retrieval and removal of an intravascular filter which has been emplaced in a patient, including the method or means of guidance of the retrieval apparatus throughout the various steps of the retrieval and removal process.
In order to help “visualize” the placement, positioning and orientation of an emplaced IVC filter for purposes of retrieval and ultimately removal, the currently performed procedure uses fluoroscopic guidance. This procedure uses a percutaneous retrieval set and fluoroscopy suite. Further, transport of the patient to the fluoroscopy suite is required and this can be difficult and time consuming, especially for trauma patients. While a removal hook is a structural part of the IVC filter construction which is described herein, that removal hook still must be located in some fashion and the orientation of that hook must be visualized when it is going to be used as part of the retrieval procedure.
The retrieval procedure according to the present disclosure uses an intravascular ultrasound (IVUS) transducer for visual guidance of the retrieval apparatus, the IVC filter and the steps associated with the overall retrieval and removal procedure. Included as part of the retrieval apparatus is a snare which is designed so that it can be easily seen and located under IVUS guidance. By incorporating the IVUS transducer into the retrieval apparatus, including the use of a dilator, the retrieval procedure can be performed through a single access point. Performance of a retrieval procedure under ultrasound guidance is not possible using currently approved (prior art) technology. The imaging and visualization provided by the exemplary embodiment affords the clinician a higher confidence level in the procedure and results in a safe procedure.